package demo.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {

    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    static {
        Properties properties = new Properties();
        try {
            InputStream inputStream = JDBCUtils.class.getClassLoader().getResourceAsStream("db.properties");
            properties.load(inputStream);

            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            username = properties.getProperty("username");
            password = properties.getProperty("password");

            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
    // 线程本地存储
    static ThreadLocal<Connection> threadLocal = new ThreadLocal<>();
    /*
     * 获取数据库连接
     * @return
     */

    public static Connection getConnection()  {
        Connection connection = threadLocal.get();
        try {
            if (connection == null){
                connection = DriverManager.getConnection(url, username, password);
                threadLocal.set(connection);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return connection;
    }

    public static void closeAll(Statement statement, ResultSet rs){
        try {
            if(rs!=null){
                rs.close();
            }
            if(statement != null){
                statement.close();
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }

    public static void begin(){
        Connection connection = getConnection();
        try {
            connection.setAutoCommit(false);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void commit(){
        Connection connection = getConnection();
        try {
            connection.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                connection.close();
                threadLocal.remove();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void rollback(){
        Connection connection = getConnection();
        try {
            connection.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            try {
                connection.close();
                threadLocal.remove();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}
